HOUSTON, June 24 (Reuters) - Tropical Storm Debby meanderedslowly to the Florida coast on Sunday, bringing strong winds andwaves that forced the closure of about a quarter of offshore oiland gas production in the Gulf of Mexico and spawning tornadoesthat killed one person.

Debby, the first named storm of 2012 to enter the Gulf ofMexico, was centered about 115 miles (185 km) south-southwest ofApalachicola, Florida and was nearly stationary, the NationalHurricane Center said in its 7 p.m. CDT (0000 GMT) update.

Citing a "significant change in the forecast track," the NHCsaid Debby is expected to hit the Florida Panhandle near PanamaCity on Thursday as a tropical storm. "This forecast remainsuncertain due to weak steering currents," the NHC said.

The NHC had previously predicted that the storm would trackwestward toward the Louisiana coast as a weak hurricane,spurring Louisiana Governor Bobby Jindal to declare a state ofemergency.

Debby has already disrupted nearly a quarter of Gulfoffshore oil and natural gas production as big offshoreoperators like BP Plc and Royal Dutch Shellevacuated workers from offshore platforms in the path of thestorm.

The disruption could worsen in coming days, with Debbyexpected to enter some of the most prolific production areas ofthe Gulf, home to 20 percent of U.S. oil production and 6percent of natural gas output..

Earlier on Sunday, it spawned tornadoes that killed a woman,severely injured a child and wrecked homes in central Florida inrural Highlands County, according to an emergency managementofficial.

In Alabama, a swimmer who went missing off the coast ofOrange Beach is presumed drowned, according to the U.S. CoastGuard. Several Alabama beaches were closed due to rough surf.

The NHC maintained a storm warning for theMississippi-Alabama border, extended warnings for Florida'snorthwest coast to Englewood, and discontinued warnings for theLouisiana coast. Residents were warned to expect stormconditions within 36 hours.

"Tropical storm conditions are already near or over portionsof the northeast Gulf Coast and are expected to reach theremainder of the warning area tonight," the forecasters warned.